An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Environmental Modeling Community of Practice

Surface Water Models to Assess Exposures

The EPA Center for Exposure Assessment Modeling (CEAM) distributes simulation models and database software designed to quantify movement and concentration of contaminants in lakes, streams, estuaries, and marine environments.

Available Products

The following surface water models were developed by the U.S. Environmental Protection Agency in conjunction with other government, academic, and commercial institutions. To find out more about a particular model, click on a hyper-linked model name in the table below. The models listed are available for download and are subject to the CEAM distribution and support policy.

Product Name Operating System Key Words Maintained By
AQUATOX Windows aquatox, simulation model, fate prediction, aquatic systems, effect on ecosystem, ecological risk assessments, aquatic ecosystem CEAM
BASINS Win XP, Vista, 7, 8 multipurpose environmental analysis system, watershed management, water quality, tmdl, gis framework, analytical components, ndpes CEAM
DFLOW Win XP, Vista, 7, 8 stream flows, low flow analysis, design flow statistics, daily stream flow records CEAM
EFDC Win 98, NT, 2000, XP surface water, hydrodynamic, sediment-contaminant, eutrophication, rivers, lakes, reservoirs, wetlands, estuaries, coastal ocean regions, assessment, management, regulatory CEAM
EXAMS Win 98, NT, 2000, XP aquatic biology, assessment, biology, chemistry, compliance, environmental effects, metals, NPS related, permits, pesticides, point source(s), rivers, streams, surface water, test/analysis CEAM
EXPRESS Win 98, NT, 2000, XP przm, exams, exposure, shell CEAM
GCSOLAR Windows 7,8,10 solar, photolysis, half-life, pollutant, aquatic, ozone CEAM
HMS Web Services hydro-informatics, hydrologic micro services, environmental modeling, water quality data provisioning web services, modeling components, precipitation, air temperature, solar radiation, soil moisture, evapotranspiration, surface and subsurface flow, runoff. CEAM
HSCTM2D Win 9x, NT hydrology, sediment, contaminant, transport, finite element model, river, estuary CEAM
HSPF Windows XP, Vista, Windows 7, or Windows 8 assessment, biology, compliance, deposition, discharge, environmental effects, estuaries, hydrology, lakes, metals, monitoring, NPS related, NPDES, nutrients, permits, pesticides, point source(s), rivers, sediment, streams, surface water, test/analysis, TMDL related, toxicity CEAM
Low Flow Text only definition and characteristics, low flows, aquatic life criteria, design flows CEAM
PRZM3 Win 98, NT, 2000, XP assessment, discharge, environmental effects, hydrology, land use management, metals, pesticides, surface water, test/analysis CEAM
QUAL2K Exit Win ME, 2000, XP aquatic biology, assessment, compliance, discharge, environmental effects, hydrology, NPS related, NPDES, point source(s), surface water, test/analysis, TMDL related EPA Region 4
RUSLE2 Exit Win 98, NT, 2000, XP rill, interrill, erosion, sediment, overland flow, climate, soil, topography, land use USDA Agricultural Research Service Exit
SERAFM MS-Excel 2003 serafm, exposure, assessment, mercury, hg, surface water, pond, stream, river CEAM
SWMM Win 98, NT, ME, 2000, XP aquatic biology, assessment, combined sewer, community, discharge, environmental effects, metals, NPS related, NPDES, point source(s), procedure, rivers, stormwater, streams, surface water, test/analysis, TMDL related Center for Environmental Solutions and Emergency Response (CESER)
Surface Water Toolbox Exit Win 7, 8 Water Resources, Groundwater and Streamflow Information Program, n-day frequency analysis, compute biologically-based design flows, Flow duration curves US Geological Service (USGS) Exit
Virtual Beach MS Windows surface water, water bodies, beach, pathogen predictor, multiple linear regression, MLR, best-fit model CEAM
Visual Plumes Win 98, NT, 2000, XP surface, water, jet, plume, model, quality, contaminant, TMDL CEAM
WASP Early versions of Windows, 64-bit Windows 7 or higher, Mac OSX, Linux Ubuntu aquatic biology, assessment, compliance, discharge, environmental effects, hydrology, metals, NPS related, NPDES, point source(s), surface water, test/analysis, TMDL related CEAM
WHATIF Win XP(SP2) watershed, health, fish, habitat, macro-invertebrate, biodiversity, BASS, biomass, biota, aquatic ecosystem, MAHA, CVI, hydraulic, bankfull, flow, restoration, food web, mercury, PCB, dioxin CEAM
WMOST Windows Excel 2010, 2013, 2016 with Macros Integrated Watershed Management, Optimization, Decision-Support, Green Infrastructure, Tool CEAM